Controlling Molecular Conformation Before Passage Through A Nanopore

We present a device to pre-stretch DNA before translocation through a solid-state nanopore, taking advantage of a recently developed ultra-thin nanoporous membrane positioned within nanometer distances from a sensing nanopore fabricated by controlled breakdown. This nanofiltered nanopore essentially creates a nanopore device with two pores in series, which reveals fundamental physics of polymer translocation previously hidden in the noise. We show experimental results that demonstrate that the fluctuations in the passage time of translocating DNA molecules can be reduced by controlling the molecular conformation during capture by a nanopore. Furthermore, this reduction in spread is found to be independent of the pore dimensions and stability, enabling consistently narrower passage time distributions and more reliable polymer size separation regardless of the characteristics of the nanopore. Remarkably the presence of the nanofilter upstream of the sensing nanopore can also help to suppress folding of translocating DNA, ensuring single-file molecular passage. These unique attributes will offer significant practical advantages to many solid-state nanopore-based technologies, including sequencing, genomic mapping, and barcode detection for diagnostics.